Effects of high nitrogen nickel-free stainless steel on the adhesion of human umbilical vein endothelial cells（HUVECs） and blood platelets were investigated.The blood platelets adhesion test and blood hemolysis rate were used to evaluate the blood compatibility of high nitrogen nickel-free stainless steel.Human umbilical vein endothelial cells（HUVECs） were cultured in vitro,using MTT cytotoxicity test,cell adhesion test,to evaluate the cell compatibility of high nitrogen nickel-free stainless steel.Results showed that the hemolysis rate of high nitrogen nickel-free stainless steel was well below the accepted threshold value of 5%,but the effect on platelet adhesion was not obvious;the number of HUVECs adhesion on surface of high nitrogen nickel-free stainless steel were significantly more than that on the surface of titanium,and the cells in the surface showed a good growth situation.MTT test showed that both the high nitrogen nickel-free stainless steel and titanium alloy had no obvious effect on the HUVECs.

The aim of this study is to construct a biocompatible coating of a drug-eluting stent through the incorporation of chitosan with monoclonal antibody (mAb) to a platelet glycoprotein (GP) IIIa receptor, by electrostatic layer-by-layer (LBL) adsorption of oppositely charged polyelectrolytes and proteins. The platelet maximum aggregation rate and aggregation inhibition rate tests confirm the bioactivity of mAb in different pH assembly environments. The fluorescence spectra test and confocal laser scanning microscopy observation were used to monitor the LBL assembly process of the mAb/chitosan multilayer on the surface of the aminolyzed Poly-L-lactic acid (PLLA) membrane, when using Rhodamine B isothiocyanate-labeled mAb and Fluorescein isothiocyanate-labeled chitosan. The in vitro platelet adhesion experiment demonstrated the amicable blood compatibility of the mAb/chitosan multilayer. The endothelial cell adhesion and migration test revealed that the multilayer could improve the cytocompatibility of the PLLA matrix in terms of cell attachment, proliferation, and migration. An in vitro perfusion circuit was designed to evaluate the release rates measured by a radioisotope technique with ¹²⁵I-labeled GP IIIa mAb. The different eluting curves of the mAb/chitosan-assembled stent and mAb physically absorbed stent showed the improvement of mAb's release character when using LBL self-assembly technology. Our method to prepare a biocompatible stent surface with mAb/chitosan multilayers has proved to be favorable and effective in vitro, thus justifying further evaluation to improve the biocompatibility in an animal model test.

In this study, two kinds of hydrogel membrane were developed. One was a hydrogel membrane which contained polyvinyl alcohol (PVA), dimethyl sulfoxide (DMSO) and porcine small intestinal submucosa (SIS) powders. Another was a hydrogel membrane consisting of PVA and SIS, but not DMSO. These two kinds of material both were crosslinked by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N- hydroxysuccinimide (NHS). The results of mechanical and biocompatible testing showed that mechanical properties, blood and cell compatibility of the hydrogel membranes were changed when the DMSO was added in PVA-SIS system. Hemolysis rates of PVA-DMSO-SIS and PVA-SIS hydrogel membranes were calculated to be 0.8% and 0.5%, respectively. The number of adherent platelets on PVA-DMSO-SIS membrane was about 20% of the PVA-SIS, and there was no sign of accumulation, and almost no pseudopodium could be observed. The endothelial cell adhesion and growth text showed that the endothelial cells were amicable with the two kinds of hydrogel membrane and the endothelialization property of PVA-SIS membrane was better than that of PVA-DMSO-SIS membrane. These results demonstrated that PVA-DMSO-SIS and PVA-SIS hydrogel membranes had potential biomechanical and biological properties as a novel biomaterial for intravascular applications.

An eluting-stent system with mAb dispersed in the PLLA (poly (L-lactic acid)) was validated in vitro. Specifically designed spray equipment based on the principle of ultrasonic atomization was used to produce a thin continuous PLLA (poly (L-lactic acid)) polymer coating incorporating monoclonal antibody (mAb). This PLLA coating was observed in light microscopy (LM) and scanning electron microscopy (SEM). The concentration of the monoclonal antibody (mAb) to the platelet glycoprotein (GP) IIIa receptor and the eluting rate were then measured by a radioisotope technique with 125I-labelled GP IIIa mAb. An in vitro perfusion circuit was designed to evaluate the release rates at different velocities (10 or 20 ml min−1). The PLLA coating was thin and transparent, uniformly distributed on the surface of the stent. Three factors influenced its thickness: PLLA concentration, duration and gas pressure. The concentration of mAb was influenced by the duration of absorption and the concentration of the mAb solution; the maximum was 1662.23 ± 38.83 ng. The eluting rate was fast for the first 2 h, then decreased slowly and attained 80% after 2 weeks. This ultrasonic atomization spray equipment and technological process to prepare protein eluting-stents were proved to be effective and reliable.

To develop a novel coating material for coronary covered stents, we prepared a kind of composite membrane which contains polyvinyl alcohol (PVA) and porcine small intestinal submucosa (SIS) powders crosslinked and heparinized by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The amount of immobilized heparin increased with increasing ratios of EDC:heparin, and the maximum amount was approximately 60 µg heparin per milligram SIS powder at a weight ratio of EDC:heparin of 2. Uniaxial tensile and balloon inflation testing suggested that the composite membrane crosslinked by lower EDC concentration is more flexible and elastic. The clotting time (APTT and PT) of the heparinized PVA-SIS membrane was longer than that of the unheparinized membrane. The number of adherent platelets on the heparinized PVA-SIS composite membrane was about 25% of the unheparininzed, and there was no sign of accumulation and almost no pseudopodium was observed. The endothelial cells were amicable with the heparinized and unheparinized PVA-SIS composite membranes. In in vivo implantation tests, we observed a thin capsule formed by several layers of fibroblasts surrounding the implants. These results showed that the heparinized PVA-SIS composite membrane has potential biomechanical and biological properties as a coating material for coronary covered stent.

To prepare the dexamethasone-eluting intravascular stents by dip coating and then to observe the character of drug delayed release in vitro and in vivo in the stents. Methods Stents were prepared by dip coating. High performance liquid chromatography (HPLC) was used to detect the drug loading of the stents. The weight of bare stents and drug eluting stents was determined in order to know the weight percentage of drugs in the coating. Thermal analyzer was used to analyse the melting point of dexamethasone. The drug slow-release rate in vitro was detected with the flow chamber. The buffer solution was taken out at the scheduled time. The dexamethasoneeluting intravascular stents were implanted into the rabbit abdominal aorta. The tissues of the vessel wall and liver were employed for the detection of the drug slow-release properties in vivo. The data collected were analyzed by using SPSS 12.0. Results The drug loading level increased in a time-dependent manner and peaked 93.15 µg at 4 d. The level of the loaded drug in the coating was (13.70±0.84)%. Differential scanning calorimetry (DSC) indicated that the melting point was 259.3°C, accordant with the related literatures. Drugs were released slowly and the release rate reached 84% at 15 d. The drug concentration was detected after stent implantation. Conclusion Drugs remained 16% of the total loaded drug at 15 d and the drug concentration in the vessel wall and liver tissues was detected after stent implantation, suggesting that the prepared stents may be helpful for the slow-release of dexamethasone.

Drug-eluting stents (DES) have emerged as a recognized alternative to treat stent restenosis but many questions remain regarding the optimal type and eluting characteristics of both drug and stent. The first component of the study examines the extent of surface coating of PLLA (poly(L-lactic acid)) on a Nitinol stent. The second characterizes the adsorption and elution rates of monoclonal mouse anti-human platelet glycoprotein (GP) IIIa antibody SZ-21 from a PLLA-coated surface. The PLLA coating was examined by fluorescence staining and image analysis using the Image Processing Box of MATLAB. Stents exposed to the monoclonal mouse anti-human platelet GP IIIa antibody were tested for their adsorption characteristics by radioisotope technique with (125)I-labelled SZ-21. The elution rates were then measured in looped circuits at different velocities (10 or 20 ml/min) and durations (30 min up to 312 h). Results showed that the fluorescence staining and image analysis showed a striking difference in the extent of coating between PLLA-coated stents and SZ-21 eluting stents on the gray-scale distribution of Nitinol surfaces. The amount of SZ-21 adsorbed onto the PLLA-coated stents was dependent on the concentration and duration of immersion in the solution. The method of preparation the mAb eluting stent significantly influenced the elution characteristics for a continuous perfusion of more than 300 h. The eluting curve was biphasic with initial rapid elution for the first 24 h followed by a gradual slow elution. These results indicate that the Image Processing Box of MATLAB appears to be a useful method for semi-quantitative analysis of fluorescence images. Furthermore, SZ-21 can be passively adsorbed onto PLLA-coated stents and predictably influenced by the concentration and duration of immersion. These studies may pave the way to developing stent-based delivery of a potent anti-platelet agent.

In order to prepare the polymer coating effectively and simply on the stent, which avails producing the drug eluting stent (DES), a novel micro-spraying system was introduced in this paper. Based on the theory of ultrasonic atomization, the spray system was designed and established which was composed of four primary modules. The optimized spray parameters were also determined through orthogonal experiment for preparing coating by the system. The fluorescence stain and image analysis were used to make the morphologies of coating more apparent. Our experimental results reveal that the spray system designed in this paper is suitable for preparing polymer coating, which will facilitate the development of DES.

Objective To prepare the coating of dexamethasone-eluting intravascular stent and observe the features of its delayed release in vitro.Methods Spray painting and dipping coating were used respectively to prepare stent coating,and then high performance liquid chromatography(HPLC)was used to detect the drug loading.The stents prepared by dipping coating were set in a flow of 50 ml PBS buffer at a velocity of 20 ml/min,and 0.5 ml buffer was collected at 6 h and 1,2,4,6,8,10,12,15 d respectively with another 0.5 ml fresh PBS being added immediately.The drug content of the 0.5 ml buffer was detected by HPLC for drug sustained release in vitro.Results The drug loading of stents prepared by spray painting was(24.26±5.23)μg,while that stents prepared by dipping coating for 4 d was(93.15±7.83)μg.Drugs were released slowly and the release rate reached 84% at 15 d.Conclusion The dipping coating-prepared stents have evident effect of sustained release.

In order to prove the feasibility of preparation of the drug-incorporated stent by immersing stent wires in the monoclonal antibody (mAb) solution, fluorescence stain and image analysis were used to evaluate the L-PLA-coated stent. Absorption was measured using a radioisotope technique after preparing the mAb-incorporated stent, and the absorption curve was determined from the absorption data. In an in vitro perfusion circuit, the antibody was eluted from the stent matrices, and the related influence factors were evaluated based on the release data.

Researches on drug-eluting stents are now focusing on three main aspects: the stent materials, the coating matrix material and the selection, adhesion and controlled release of the biological agents. The current development progresses of the coating materials, their characteristics, and the coating method for metallic stents are reviewed in this paper.

To examine the effects of vigorous physical activity (PA) on intra-abdominal fat (IF) levels in obese men.Thirty-seven obese men (mean age: 47.6 ± 8.6 years) engaged in a 12-week aerobic exercise program on a regular basis (3 days/week). We divided them into low volume of vigorous PA group (n = 19) or high volume of vigorous PA group (n = 18), based on the median time spent (34.3 min/week) in vigorous PA (over 6.1 metabolic equivalents assessed by a single-axis accelerometer) throughout the program.Regular exercise reduced IF levels (measured by computed tomography) from 188.1 ± 53.9 cm2 to 170.3 ± 46.6 cm2 for the low volume of vigorous PA group and from 167.9 ± 44.3 cm2 to 137.9 ± 40.6 cm2 for the high volume of vigorous PA group. Two-way (time × group) ANOVA revealed no significant interactions for the IF level. However, correlation analysis for all participants showed that time spent in vigorous PA throughout the program significantly correlated to IF reductions after adjusting for initial levels of IF, vigorous PA and weight changes (r = −0.42, P = 0.02).This study suggests that vigorous PA may affect IF reductions in obese men.

Spherical hollow titania materials with a diameter of 60-100 nm and wall thickness of approximately 10 nm were synthesized using nanosized CaCO3 particles as inorganic templates. BET surface area of as-synthesized titania was 381.15 m(2)/g, and decreased to 124.36 m(2)/g after calcination at 500degreesC for 2 h.

本文以聚乳酸（PLA）膜为基底，利用氨解反应及静电层层自组装技术，使抗血小板膜糖蛋白单克隆抗体SZ-21和壳聚糖交替吸附于膜表面, 形成复合层状结构，并利用扫描电镜、红外光谱检测、接触角检测考察和跟踪组装过程，最后采用血小板黏附实验、溶血率实验以及内皮细胞黏附实验进一步考察复合层的血液相容性和细胞相容性。相关实验结果表明经过氨解反应可以成功将自由氨基接枝于PLA表面，单克隆抗体药物和壳聚糖能够通过静电层层自组装技术在聚乳酸膜表面构建复合涂层，经过改性后的涂层结构具有良好的血液相容性和细胞相容性。本研究材料可能为新型药物血管支架提供选择。

本文基于超声雾化的原理，选择水位控制型投入式雾化器设计并实现一种微量喷涂装置，可用于结构复杂的网孔支架类心血管器械表面涂层制备，并以几何结构较为复杂的血管内支架作为模式实验材料，利用扫描电子显微镜和扫描探针显微镜相结合观察涂层表面微观形貌，证实微喷涂系统的可行性与有效性。结果表明，涂层表面平整均匀，边缘平滑，没有聚集或凝结现象出现，证明该微喷涂系统可以用于网孔支架类心血管器械的表面涂层制备。